It has been known to arrange granular cleaning devices in a double bank configuration as shown for example in U.S. Pat. No. 4,234,416 of Nov. 18, 1980, Lower et al. In that device, the screening machine is arranged in a multiple deck configuration with the feed material being divided into separate, equal fractions as it falls into parallel vertical channels. Each of these channels is directed to a particular screen deck by way of a chute that diverts the respective feed from the channel onto the screen. However, there are disadvantages in such known devices in that the sets of decks are actually two pairs, discharging the feed material towards the center. The infeed is split to feed both sides of the machine, the length of each cleaning deck being restricted to the distance from the side of the machine to a point adjacent the center as shown for example in FIG. 1 of the Lower patent. It will be seen from that Figure as well as from FIG. 2 of the patent that the feed is directed down the sides of the machine onto the decks which slope toward the center.
Conventional machines have also been supported on the wire ropes and the like, the strands in the rope eventually fraying and being subjected to failure.